The test to kill all three variables in one step is the F test with test stat 12.82165585 and you compare it to an .
The p-value is and the printout gives that value as 7.48476E-06.
So as long as , you reject which is that all three variables can be dropped.
But with such a small p-value the conclusion is that we do indeed need at least one of those three terms to explain these people's salary.